Background Small automated dispensing systems (ADS) have allowed improvements in the hospital drug distribution process. The pharmacy department is responsible for filling small ADS with medications in a timely manner, ensuring continuity of care.

Purpose To analyse the causes of stock-out in small ADS and propose improvement actions.

Material and methods A prospective study was performed over 1 month (May 2015). Seven small ADS (Pyxis) were allocated to five units in a tertiary hospital (emergency department, postoperative care unit, pre-hospitalisation unit, short stay unit and neonatal intensive care unit). Each day a list of stock-outs for the day before was obtained and classified by unit using Web-Reporting software, and the causes for each one were investigated. Five reasons were established:

• Shortage: pharmacy supplier cannot provide the requested order.

• Insufficient stock: in a certain small ADS, fixed/agreed stock is not suitable for consumption.

• Inadequate pharmacy management: when an order was not sent to the supplier, or the order was sent so late to avoid the stock-out; pharmaceutical dosage forms which require packaging delayed the distribution process.

• Inadequate maintenance of the small ADS database: formulary and/or stock of drugs are not correctly updated in the database.

• Other: any stock-out for other reasons, such as expired drugs, broken containers, inventory discrepancies, etc.

Results During the study period, a total of 482 stock-outs were detected. The emergency department and postoperative care unit had 36.3% each, and both had two small ADS. These results were distributed as follows:

• Shortage: 65.4%. These were isolated or permanent during the study period.

• Insufficient stock: 21.2%; 52.0% took place on weekends because no resupply was done.

• Inadequate pharmacy management: 6.8%.

• Inadequate maintenance of the small ADS database: 1.6%.

• Other: 5.0%.

Conclusion A high number of stock-outs occurred, and the main cause was the shortage of drugs, which is sometimes unavoidable. To reduce the other preventable causes, the pharmacy department has planned the following actions: to readjust the locations and stocks of drugs, to improve pharmacy management, to check and update the database and to give training for nurses to improve the use of small ADS.

No conflict of interest.